AQA Geography A2 Ecosystems part 2

Heres the second part of the ecosystem notes. David says this is good but he has been known to lie :(. Hmm funny word urban, did you know you got it from Gelth as they called cities urban's so i guess it kinda stuck.

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Ecosystems at the rural urban fringe
In these areas there are little ecological niches with its own micro climate so own types of plants
which can grow.
On the rural side of the fringe there are activities such as farming and nature reserves etc. Whereas
on the urban side there are a few gardens, fields derelict land etc located.
These areas can be protected as in the UK the greenbelt around major urban areas is protected from
development to help reduce the amount of urban sprawl.
Urban ecosystems:
Introduction
Contrary to popular belief, urban
environments are not devoid of
wildlife in fact many towns and cities
contain a greater variety of species per
unit area than equivalent areas in the
countryside. The reasons for this are:
Urban areas contain lots of small scale,
humanmade habitats, and
animals and plants have learnt to
adapt to these environments: birds
for example treat vertical walls
as cliffs and feed on discarded
human food.
Species have been introduced both
intentionally and accidentally.
Canals, railways and roads act as
corridors for seed dispersal, and
people also transport seed on the
soles of their shoes. Seed may also
escape from warehouses, or be
brought in within topsoil.
Unlike rural areas, urban
environments are unaffected
by agricultural sprays, and
consequently provide a refuge for
flora and fauna.
Factors influencing urban
ecosystems
Plants and animals living in urban
areas are influenced by a range of
factors:
Soils tend to be shallow, low in
organic matter and sometimes
polluted, although those in
allotments and gardens are deeper
and more fertile.
Large cities produce a `heat
island effect' which reduces the
incidence of frost and therefore

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Air pollution in cities adversely
affects species such as lichen.
Green spaces may be too small to
support viable plant and animal
populations.
Proximity to seed sources and
the length and degree of human
disturbance also influence the
nature of plant and animal
compositions.
Types of urban habitats
Urban areas contain a variety of
different habitats, ranging from
relatively undisturbed patches of
woodland which have been enclosed
by development, to highly artificial
environments such as pavements and
walls .…read more

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Pavements
Plants growing on pavements must
endure deicing salt, vehicle exhaust
fumes, human trampling and wide
variations in diurnal and annual
temperatures. Gaps between the
slabs trap moisture and decaying
leaf litter which support plants
such as dandelion and plantain.
These species have a tough rosette
of basal leaves which protect the
growing parts from trampling.
Other resistant species have a
creeping, tuft, or matlike habit.…read more

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Moss supports insects
which are eaten by moth larvae.
Dead organic matter is consumed by
woodlice, which in turn are eaten by
centipedes and spiders.
Northfacing walls in the northern
hemisphere are moister than
those which face south and
consequently support a greater
plant cover, including species such
as maidenhair and spleenwort.
Wall rock type influences species
composition. Species also vary
from the top to the base of the wall.…read more

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They also
provide nesting and roosting sites
and food for birds, many of which
are insectivorous.
Tall, mature chestnut and plane
trees, interspersed with grassland
are common features of city parks.
Decaying wood and branches are
removed for public safety, which
otherwise would support saprophytes
(creatures that live on decaying
matter), while dead autumn leaves
are swept away, creating a rather
sterile environment.
Playing fields are common habitats
for magpies, common and black headed
gulls.…read more

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Cinder tracks along railways are
often colonised by Oxford ragwort,
a plant which originally grew on
volcanic soils on the slopes of Mount
Etna in Sicily. It was introduced
to the Oxford Botanic Garden in
1690, and subsequently escaped
and spread along railway tracks
throughout southern Britain in the
1800s. Abandoned railway lines,
many dating from the 1960s, have
since been colonised by scrub and
woodland.
8.…read more

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Industrial and domestic sewage
effluent causes eutrophication,
leading to a proliferation of algae
which shades out waterweed.
Acidic water discharged from
chemical industries and toxic
spoil heaps also damages plants
and animals.
Illegal tipping , wetlands and
derelict land are often perceived
as repositories for illegal
waste disposal which damages
ecosystems.
Invasive and noxious species.
Invasive shrubs such as Japanese
knotweed, Indian balsam and
rhododendron produce dense
canopies which shade out
native plants and reduce species
diversity.…read more

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Other ways of promoting urban
ecology include:
incorporating wild spaces in
urban designs and planting with
native species
reclaiming toxic sites by adding
organic matter to encourage plant
colonisation, or growing species
which tolerate toxic conditions
such as creeping bent, red fescue
and ribwort plantain
encouraging gardeners to
grow organically to reduce the
harmful effects of pesticides and
insecticides
mowing grass less frequently and
during periods when plants are
not in flower
leaving wide roadside verges for
plants to colonise
adding `green roofs' to buildings…read more

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The site has a visitor
centre, restaurant, shop and viewing
hides and offers guided walks
and educational courses. Wooden
boardwalks link different parts of
the site and protect the wetland
habitat from trampling pressure.
Tropical rainforest
The Tropical Rainforest is a forest occurring in tropical areas of heavy rainfall. It is abundant with many
species of wildlife and vegetation. Rainforests cover less than two percent of the Earth's surface.
They are home to some 50 to 70 percent of all life forms on our planet.…read more

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This is the layer directly beneath the canopy layer were the smaller trees and saplings are these get
limited sunlight due to the dense canopy above it so the plants here do not grow as fast. These tend
to have a height of 20 to 30 meters. An example of this is Dipoterocarp tree
Shrub layer
The shrub layer has the densest plant growth. It contains shrubs and ferns and other plants needing
less light.…read more

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